Process using iron-thallium catalysts in CO hydrogenation

ABSTRACT

CO hydrogenation process is described utilizing novel thallium-promoted iron catalysts. Mixtures of CO/H 2  are selectively converted to liquid C 6  -C 11  hydrocarbons containing C 6  -C 11  aromatics, alpha olefins and very small amounts of C 23  + hydrocarbon waxes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of U.S. Ser. No.299,014, filed Sept. 3, 1981 abandoned.

BACKGROUND OF THE INVENTION

The Fischer-Tropsch process is one of several processes involving thehydrogenation of carbon monoxide and is well-known for producinghydrocarbons and hydrocarbon fuels by contacting mixtures ofcarbon-monoxide/hydrogen, with generally an iron-based catalyst. Theproduced hydrocarbons usually contain a broad range of liquid paraffinsand olefins of C₅ -C₂₀ carbon number, and under conditions of excesshydrogen, an especially valuable portion being the linear and branchedparaffinic C₆ -C₁₁ fraction, the well-known "gasoline" fraction usefulfor internal combustion engines.

An extensive amount of work has been carried out in an effort to modifyand improve the selectivity of the process in producing the gasolinefraction directly under efficient process conditions, having improvedoctane number. Particular process conditions which are highly desirableto achieve these goals are high percent CO conversion, low methane make,high liquid hydrocarbon make containing aromatics and olefins in the C₅-C₁₁ hydrocarbon fraction and a low wax make (i.e., C₂₃₊ hydrocarbons).

A commercially practiced Fischer-Tropsch process uses mixtures of carbonmonoxide/hydrogen that are contacted with a potassium-doped ironcatalyst, as a fluid bed, at about 320° C. to 330° C. under pressure.However, a significant quantity of wax formation occurs, and further,the resulting liquid hydrocarbons generally only comprise about 5 weightpercent aromatics.

What is desired in the art is a process which is more selective inproducing C₆ -C₁₁ liquid hydrocarbons and in producing aromatics andolefins particularly in the C₆ -C₁₁ liquid hydrocarbon portion.Particularly desired is where the process can be conducted under veryefficient conditions of high percent CO conversion, high liquidhydrocarbon make, containing C₆ -C₁₁ aromatics and/or alpha olefins, lowmethane make and low C₂₃₊ hydrocarbon wax make.

SUMMARY OF THE INVENTION

It has been found that a composition comprising a mixture of ironcompounds and thallium compounds is an efficient catalyst in a COhydrogenation process for selectively promoting the production of C₆-C₁₁ liquid hydrocarbons, containing C₆ -C₁₁ aromatic hydrocarbonsand/or alpha olefins at high percent CO conversion with attendant lowmethane and wax production.

The catalyst composition contains compounds of iron and thallium in aniron-thallium weight ratio of 100:1 to 1:100, respectively, taken as thefree metals, and the composition can be supported or unsupported andcontain catalyst promoter agents and additives as well. In a preferredembodiment, the iron value in the composition is initially substantiallyin the trivalent state. To achieve high selectivity to hydrocarbons, andpreferably C₆ -C₁₁ liquid hydrocarbons and C₆ -C₁₁ aromatics, it isnecessary to pretreat the catalyst to convert the initially trivalentiron substantially to reduced and carbided iron. The initially trivalentand/or monovalent thallium is reduced to zero valent thallium duringthis pretreatment. Thus, the preferred catalyst, in its working state,consists of reduced and carbided iron promoted by metallic thallium. Ithas been found by thermal analysis techniques, that the monovalentand/or trivalent thallium is reduced to metallic thallium first duringpretreatment and that metallic thallium promotes the subsequentreduction of oxidized iron to metallic iron and iron carbide.

The hydrocarbons produced in the process comprise gaseous C₁ -C₄hydrocarbons and C₅ -C₂₃ liquid hydrocarbons, including linear andbranched paraffins and olefins, together with small amounts ofoxygenates such as methyl alcohol or ethyl alcohol. The amount of C₂₃₊hydrocarbon waxes is generally about 5 weight percent or less andpreferably less than about one weight percent. The ratio ofparaffins/olefins produced in the process can be regulated by thehydrogen partial pressure, i.e., increasing the H₂ partial pressureincreases paraffins/olefins ratio. In addition, in the process, alphaolefins are obtained in good yield in the temperature range of about270° to 350° C., and aromatics in the C₆ -C₁₁ liquid fraction areobtained in good yield at temperatures above 350° C. The C₆ -C₁₁ liquidhydrocarbons produced usually comprise about 40 weight percent and aboveof the total hydrocarbons produced, and of the liquid hydrocarbonsproduced, about 65 weight percent and greater is comprised of C₆ -C₁₁hydrocarbons. The gasoline fraction, the C₆ -C₁₁ fraction, generallycontains about 5 weight percent or greater of aromatic C₆ -C₁₁hydrocarbons. However, depending upon the particular process conditionsused, higher or lower amounts of the above-stated hydrocarbon productsmay be formed.

In accordance with this invention, there is provided a process forproducing liquid hydrocarbons, including those in the C₆ -C₁₁hydrocarbon range, comprising the steps of:

(a) first contacting a supported or unsupported catalyst compositioncomprising a mixture of iron compounds and thallium compounds, whereinthe weight ratio of iron-thallium, taken as the free metals, is fromabout 100:1 to 1:100, and wherein said iron compounds contain iron valuesubstantially in the trivalent state, by contacting said catalyst with amixture of CO and H₂ in a volume ratio of about 1:4 to 4:1,respectively, at a temperature ranging from 270° to 550° C., a pressureranging from 0.1 to 10 MPa and a space velocity ranging from 10 to10,000 v/v/hr., or equivalent conditions, to substantially convert saidthallium compounds to metallic thallium and said iron compounds toreduced and carbided iron; and

(b) continuing said contacting as described in step (a) at a pressureabove 0.1 MPa to produce liquid hydrocarbons comprising about 40 weightpercent and greater C₆ -C₁₁ liquid hydrocarbons and below about 5 weightpercent C₂₃₊ hydrocarbons.

DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

The catalyst composition in the process is capable of selectivelyproducing C_(6-C) ₁₁ liquid hydrocarbons from carbon monoxide andhydrogen under efficient process conditions. The C₆ -C₁₁ hydrocarbonfraction contains a significant percentage of C₆ -C₁₁ aromatichydrocarbons, produced at process temperatures above 350° C., which areextremely effective as octane-increasing agents for motor gasoline, andalpha olefins, produced at process temperatures from 270° to 350° C.being useful chemicals in the chemical industry. Further, use of thecatalyst under Fischer-Tropsch conditions results in a surprisingly lowC₂₃₊ hydrocarbon wax make. The reason why the combination ofiron-thallium compounds in a mixture is unique in producing these verydesirable results is not at all clear. One theory that we do not wish tobe bound by is that iron and thallium form a redox couple that isselective in forming aromatics and other hydrocarbons under the processconditions.

The performance of thallium promoted iron catalysts is similar in somerespects to conventional commercial potassium promoted CO hydrogenationcatalysts. However, thallium promoted iron catalysts provide thefollowing advantages over potassium promoted iron catalysts: no need forsintering or other high temperature treatment during catalystpreparation (K promoted catalyst preparation usually requires sinteringat temperatures above about 500° C. to achieve intimate Fe-K contact inthe catalyst mixture); no significant wax formed (K promoted ironproduces several percent wax); and very high activity, especially atlower space velocities and higher temperatures.

The catalyst composition consists essentially of a mixture of ironcompounds and thallium compounds, wherein the weight ratio ofiron-thallium, taken as the free metals, is about 100:1 to 1:100, inwhich the iron value is regarded as being initially substantially in thetrivalent state. This is based on the fact that use of ferric compoundsin the composition and use of an oxidizing atmosphere, e.g. air, in thedrying step during preparation of the compounds leads to desiredresults. By the term "consisting essentially of", as used herein, ismeant that other materials, known in the art as being promoters,activators, supports and catalytic-aiding materials, may also bepresent, as long as the unique capability of the subject catalyst inproducing C₆ -C₁₁ liquid hydrocarbons in the absence of significantamounts of C₂₃₊ hydrocarbon waxes, is not adversely effected. By theterm "mixture of iron compounds and thallium compounds" is meant aphysical admixture, solid solution, alloy, spinel, or new compoundformed from the compounds in which the compounds can be simply combined,co-precipitated, precipitated individually, and then combined or formedby impregnating one solid compound with a solution of another to producethe composition.

A thorough description of the catalyst composition is described in arelated application, U.S. Ser. No. 418,380, filed 9-15-82, herebyincorporated by reference, which describes catalyst components andweight ratios, additives, promoter agents and the like, and methods ofpreparation.

The weight ratio of iron-thallium, taken as the free metals and referredto herein as Fe/Tl, being in parts by weight in the composition is from100:1 to 1:100, preferably from 100:1 to 35:65, particularly preferredfrom about 100:1 to 65:35 and most preferred from about 100:10 to 80:20,respectively.

The catalyst composition contains iron initially substantially in itstrivalent state in order to convert CO and H₂ to C₆ -C₁₁ aromatic andother hydrocarbons, and by the term "substantially" is meant at leastabout two-thirds of the iron present, such as in the case of Fe₃ O₄. Itis to be understood that an iron-based catalyst which is subjected tooxidizing conditions prior to CO hydrogenation, such that a significantamount of ferric ion is formed on the catalyst surface, is also regardedas being an operable embodiment and included within the scope of thesubject catalyst.

Iron compounds and thallium compounds operable in the composition areinorganic or organometallic and include their oxides, hydroxides,carbides, nitrates, carbonates, halides, sulfates, and the like, andmixtures thereof. Representative examples include Fe₂ O₃, Fe₃ O₄,Fe(OH)₃, Fe₅ C₂, Fe(NO₃)₃, Fe₂ (CO₃)₃, FeCl₃, Fe(NH₄)(SO₄)₂, Tl₂ O,TlNO₃, Tl₂ CO₃, Tl₂ SO₄, TlCl₃, TlCl, TlF and the like, preferredcompounds are iron oxide, thallium oxide, thallium chloride, thalliumfluoride, thallium nitrate, or mixtures thereof. Also preferred arewhere said iron compounds contain iron value substantially in thetrivalent state, and for purposes of this application, since the truevalence of iron in iron carbides is not exactly known, but can beassumed to be at least partially in an oxidized state, iron carbides areintended to be included within the class of iron compounds wherein theiron is substantially in the trivalent state. Also operable areorganometallic compounds of iron or thallium which decompose to therespective oxides under the process conditions, e.g., thallium acetateand iron oxalate. Preferably the thallium value is substantiallyimpregnated on the surface of the catalyst composition.

Particularly preferred compounds are the oxides of the two metals whichcan be formed, for example, by precipitating the metal values fromaqueous solution of their soluble nitrates or sulfates by the additionof a base to form the respective hydrated oxides, which are dried andheated in the presence of air and converted to the metallic oxides.Thus, a preferred composition is a mixture of iron oxide and thalliumoxide.

The subject catalyst composition can be supported or unsupported and ispreferably supported. This preference is because the supported catalysthas, in general, a longer catalyst lifetime and a lesser tendency todisintegrate during continued operation. Representative examples ofsupports include alumina, alkali-doped alumina, silica, titaniumdioxide, magnesium oxide, magnesium carbonate, magnesium silicate,silicon carbide, zirconia, Kieselguhr, talc, clay, and the like. By theterm "alkali-doped alumina", as used herein, is meant a mixture ofalumina and about 1 to 20 mole percent of an alkali metal salt, based onthe moles of alumina, such as potassium carbonate, potassium silicate,cesium carbonate and the like. Mixtures of supports can also beutilized, including those above, for example, alumina and magnesiumoxide. Preferred supports for the catalyst in the process for producingC₆ -C₁₁ aromatic hydrocarbons include cesium-doped alumina, or alumina,magnesium oxide, or mixtures thereof.

The amount of said support present can be from about 50 to 99 weightpercent, based on the combined weight of said iron/thallium compounds,said support preferably being 75 to 95 weight percent of the totalweight of catalyst composition.

Various additives and promoter agents can also be utilized with thecatalyst, including cobalt, zinc, magnesium, barium, nickel, chromium,manganese, and compounds or salts thereof, such as cobalt oxide, zincoxide, chromium oxide and the like, which increases the activity andselectivity of the catalyst and thus reduces the required temperature inthe process. Also operable are alkali metal salts, such as potassiumsalts, e.g., potassium carbonate, potassium oxide, potassiumbicarbonate, potassium hydroxide, rubidium carbonate, alkali metalborates and silicates; other metals, such as zirconium, cerium,vanadium, rare earth elements, tantalum and molybenum; and halide salts,e.g., fluoride salts such as ammonium fluoride, potassium fluoride andthe like, also for promoting the formation of liquid hydrocarbons. Inaddition, other additives/promoters can be used including, but notlimited to, alumina, manganese oxide, magnesium oxide, thorium oxide,calcium oxide, titanium dioxide and the like, to help maintain thestability and integrity of the catalyst. Preferred promoters for thecatalyst are cobalt, zinc, magnesium, as their salts or oxides, ammoniumfluoride, potassium carbonate, or mixtures thereof.

Amounts of promoters or additives that can be used in the compositionsare from about 1 to 200 weight percent, based on the weight of iron,taken as the free metals.

For example, cesium, as the carbonate salt, is generally used in about 1to 25 weight percent, cesium taken as the metal, to dope an aluminacarrier. Ammonium fluoride is used in about a 0.1 to 10 weight percent,based on the weight of iron as the free metal, as a promoter, andpotassium carbonate is used in about a 0.1 to 5 weight percent, based onthe weight of iron, as the free metal, to promote the subjectcomposition. Cobalt and zinc, as their salts or oxides, are generallyused in about a 1 to 20 weight percent, based on the weight of iron, asthe free metal, to promote the catalyst.

Representative examples of catalyst compositions are (giving thecomposition and the weight ratio of the metals or elements in the freestate) Fe₂ O₃ /Tl₂ O₃ (10:1 Fe/Tl); Fe₂ O₃ /Tl₂ O₃ /NH₄ F (100:10:2Fe/Tl/F); Fe₂ O₃ /Tl₂ O₃ /K₂ CO₃ (100:10:1 Fe/Tl/K); Fe₃ O₄ /Tl₂ O₃(10:1 Fe/Tl); Fe₂ O₃ /TlNO₃ (10:1 Fe/Tl); Fe₂ O₃ /CoO/TlNO₃ (100:52.3:10Fe/Co/Tl); and Fe₂ O₃ /ZnO/TlNO₃ (100:53.2:10 Fe/Zn/Tl).

A preferred catalyst composition is an iron oxide/thallium oxide oncesium-doped alumina, wherein cesium is present, as the metal, in about13 weight percent of the alumina; iron, as the free metal, is present inabout 10 weight percent of the combined weight of the cesium-dopedalumina; and thallium is present, as the metal, in about 10 to 20 weightpercent of iron.

The catalyst composition can be made by a variety of techniques. Thesimplest method is to mix together an iron compound and a thalliumcompound, which are finely ground, in the proper ratio, and utilize thecatalyst as is.

Another method is to co-precipitate the iron and thallium metal valuesfrom aqueous solution by the addition of base to precipitate thehydrated metal oxides. The resulting mixture is collected, washed anddried in air to yield the mixture of the corresponding oxides. Thedrying step is preferably carried out in air, and preferably under theinfluence of heat.

To insure a highly active catalyst, it is preferable to remove anyexcess alkali salts that might be initially present on the surface ofthe iron hydroxide. Also, iron exchange agents such as soluble ammoniumcompounds, can be used to wash the precipitated iron hydroxide.Alternatively, an ammonium salt, such as ammonium bicarbonate, can beused to precipitate the metal hydroxide from the solution.

A still further method of preparing the catalyst compositions is toprecipitate one metal value from an aqueous solution of its salt by theaddition of base, or adjustment of the pH of the solution, and toisolate the metal oxide thereof. The same procedure is then used for theother metal value and the two resulting metal oxides are mixed togetherto form the subject catalyst.

A particularly preferred method for making the iron-thallium catalystsis via the "incipient wetness" impregnation technique whereby a knownamount of thallium salt, such as thallium nitrate, is dissolved indistilled water and added dropwise with thorough stirring to finelydivided, solid water-insoluble iron compounds to insure even dispersionon the solid surface by the thallium salt. Uniform distribution isinsured by adding only just enough thallium solution to wet the entiresurface of the iron solid to take advantage of the surface spreadingforces.

A further method for making the catalyst composition in which at leastone preferably finely divided, solid iron-containing compound iscontacted with a concentrated aqueous solution of at least one solublethallium compound, preferably the nitrate, thereby substantiallyimpregnating the surface of the iron compound, and then drying saidimpregnated iron-containing compound in the presence of an oxidizingatmosphere, preferably air, thereby resulting in said composition,wherein said iron value is substantially in the trivalent state.Particularly preferred is where the thallium compound is substantiallyimpregnated on the surface of the catalyst composition. The resultingsolid can be air-dried at room temperature, vacuum-dried at elevatedtemperature, or preferably heat-dried in air, and then ground into afine particle size and used as is in the process.

The obtained catalyst compositions, including that prepared by thesubject method, generally has a surface area from about 5 to 300 m² /gm.After the required pretreatment in the process with, preferably, amixture of CO and H₂, the catalyst surface size reduces to about 1 to 50m² /gm.

The subject matter of the instant invention is a process for producingliquid hydrocarbons in the C₆ -C₁₁ hydrocarbon range comprising C₆ -C₁₁aromatic hydrocarbons and alpha olefins, and below about 5 weightpercent C₂₃₊ hydrocarbon waxes.

The process is conducted by contacting a mixture of CO and H₂ with asupported or unsupported catalyst composition that has been pretreatedand comprising a mixture of iron compounds and thallium compoundswherein the ratio of iron-thallium, taken as the free metals, is fromabout 100:1 to 1:100. A thorough description of operable iron-thalliumcatalysts useful in the process is given hereinabove for the subjectcomposition including weight ratios, different iron and thalliumcompounds operable, additives, promoter agents and the like, and methodsof preparation. The scope of iron-thallium catalysts operable in thesubject process is broader than for the subject composition in that itis intended to include all mixtures comprising iron-thallium compoundcombinations which result in the production of C₆ -C₁₁ liquidhydrocarbons containing C₆ -C₁₁ aromatic hydrocarbons and alpha olefins,and less than about 5 weight percent C₂₃₊ hydrocarbon waxes. Thus, theiron-thallium based catalyst useful in the process also comprises theuse of other co-catalysts, and supports, not specifically describedherein, and combinations in which the iron value may not besubstantially in the trivalent state or where the thallium value may notbe substantially impregnated on the catalyst surface. Preferredembodiments of iron-thallium combinations are described hereinabove inthe discussion of the catalyst.

By the term "mixtures of CO and H₂ " is meant mixtures of pure CO andH₂, or impure mixtures, also containing water, CO₂ and the like, andincluding "water gas", "synthesis gas", "Town gas" and the like. Apreferred mixture is that produced by gasification apparatus, such as aShell-Koppers Gasifier.

The ratio of CO and H₂ as CO/H₂, in the process is about 4:1 to 1:4,preferably 2:1 to 1:2, and particularly preferred about 1:1,respectively.

A volume ratio of 2:1 CO/H₂ can be produced by commercial coalgasifiers, and an excess of CO in the feedstream also tends to reducethe amount of light gases produced in the process.

The temperature of the process, after catalyst pretreatment, isconducted at about 230° to 550° C., preferably about 270° to 400° C. Thetemperature range between 270° to 350° C. favors alpha olefin formationand from 350° to 550° C., C₆ -C₁₁ aromatics are produced in significantquantity.

The pressure of the CO/H₂ feedstream in the process is above about 0.1MPa to about 10 MPa (1 to 100 atmospheres) and preferably about 0.5 to1.5 MPa and particularly preferred, about 0.8 MPa.

The space velocity of the CO/H₂ feedstream is maintained at about 10 to10,000 v/v/hr., preferably about 100 to 2500 v/v/hr. and particularlypreferred of about 150 to 1500 v/v/hr.

A particularly preferred embodiment of the subject process comprisescontacting a mixture of CO and H₂, in about a 1:1 volume ratio,respectively, with a supported catalyst composition, which has beenpretreated, comprising a mixture of iron oxide and thallium nitrate oroxide, the weight ratio of iron-thallium, taken as the free metals, inthe composition, being from about 100:1 to 35:65. The iron oxide of thecatalyst composition contains iron value, substantially in the trivalentstate, and thallium compound is substantially impregnated on the surfaceof the iron catalyst composition, which is supported on aluminum oxide,magnesium oxide, or mixtures thereof. The catalyst is pretreated in amixture of CO and H₂ at elevated temperature to convert the catalyst toits working form, wherein said working catalyst consists of thalliummetal and reduced and carbided iron.

The pretreatment procedure comprises heating the mixture of thalliumcompounds and substantially trivalent iron in a mixture of CO and H₂ inabout 4:1 to 1:4, and preferably a 1:1 volume ratio, respectively, to atemperature of 270° to 550° C. and preferably at about 270° C., at 0.1to 10 MPa and preferably 0.1 MPa total pressure, and a space velocity ofabout 10 to 10,000 v/v/hr, preferably 300 to 500 v/v/hr, for asufficient time to result in a reduced and carbided iron catalyst.

The hydrogen synthesis process is preferably conducted at a temperatureof about 270° to 400° C., a pressure of about 0.5 to 1.5 MPa, and aspace velocity of about 150 to 1500 v/v/hr., producing liquidhydrocarbons in the C₆ -C₁₁ range, comprised of C₆ -C₁₁ aromatichydrocarbons and alpha olefins and less than about one weight percentC₂₃ + hydrocarbon waxes. Particularly preferred embodiments are where:the product C₆ -C₁₁ liquid hydrocarbons comprise at least about 10weight percent C₆ -C₁₁ aromatic hydrocarbons at temperatures above 350°C.; 20 weight percent alpha olefins at 270° to 350° C.; and at least 40weight percent C₆ -C₁₁ liquids at 270° to 400° C. process temperatures.

The apparatus which is used for the process can be any of theconventional types, wherein the catalyst is used in the form of a fixedbed, fluid bed, slurry and the like. Preferred is the catalyst in theform of a fixed or fluid bed.

The process is generally conducted by placing the composition catalystinto the reaction zone of the reactor and pretreating the catalyst priorto the run. The pretreatment step, as described hereinabove, can beconducted by passing a reducing gas, such as H₂, CO, or NH₃, or mixturesthereof, either simultaneously or sequentially over the catalyst atelevated temperature for a certain period of time, which is dependentupon the amount of catalyst used, type of reactor and the like. Duringthis pretreatment step, the catalyst is contacted with a reducingatmosphere which converts the metal oxides to metal carbides,carbonitrides and the like, or the reduced metal, as shown by X-rayanalysis. The exact composition of the catalyst during the actual run isnot known and actually may be continuously changing in nature during therun. It is, however, believed that iron is in a reduced and/or carbidedstate substantially during the process. After the pretreatment step, thefeedstream gases, comprising CO and H₂, are passed into the catalystzone for reaction.

Methods of collecting and separating the obtained hydrocarbons areconventional and include, for example, atmospheric and reduced pressuredistillation.

The following comparative examples and examples illustrate the subjectmatter which we regard as our invention, and the examples areillustrative of the best mode of carrying out the invention, ascontemplated by us, and should not be construed as being limitations onthe scope and spirit of the instant invention.

EXAMPLE 1 Preparation of the Catalyst 100 Fe:52.3 Co:10 Tl (CatalystOne)

Two thousand ml. of an aqueous solution of 404 g. of ferric nitrate and145 g. cobalt nitrate, was heated to boiling; 1500 ml. of an aqueoussolution of 316 g. ammonium bicarbonate was added thereto with stirring.The combined solutions were heated for about 15 minutes, whereupon aprecipitate formed. The mixture was cooled, the solid filtered off andwashed with distilled water until the washings were neutral. The solidwas dried in a vacuum oven at 100° C. for 12 hours. It was removed andground to a fine particle size. The solid was then impregnated by thetechnique of "incipient wetness" by dropwise addition of an aqueoussolution of 7.3 g. thallium nitrate in 70 ml. water, whereupon all ofthe thallium nitrate solution was adsorbed by the dispersed solid. Theresulting solid was dried in a vacuum oven a 110° C. for 12 hours toyield 123 g. of dark-colored solid. Analysis of the solid revealed thatit consisted of 45.5 weight percent of iron, as the metal, and the iron,cobalt and thallium in a weight ratio of 100:52.3:10, each taken as themetal.

EXAMPLE 2 Preparation of the Catalyst 10:1 Fe/Tl (Catalyst Two)

To a boiling solution of 404 g. ferric nitrate nonahydrate in 1.5 litersof distilled water was added with stirring a solution of 237 g. ammoniumbicarbonate dissolved in 1.5 liters water resulting in the precipitationof iron oxide. The resulting solution was kept boiling until all CO₂evolution had ceased. The precipitate was filtered, washed withdistilled water until the wash water was neutral. The washed solid wasdried in a vacuum at 110° C. for 12 hours. The resulting solid wasimpregnated by the technique of incipient wetness by the dropwiseaddition to the solid of a solution of 7.3 g. thallium nitrate in 70 ml.of water. The ferric oxide adsorbed practically all of the solution. Theimpregnated solid was dried in a vacuum oven at 110° C. for 12 hours.The resulting impregnated solid weighed 86 g. an analyzed for 10 partsby weight iron, per 1 part thallium, taken as the free metals.

EXAMPLE 3

The following supported and unsupported iron-thallium catalysts wereprepared as described below.

Catalyst Three (100 Fe:10 Tl, supported on Alumina)

A solution of ferric nitrate was deposited on an alumina support toyield Fe₂ O₃ -alumina having an iron loading of about 14 weight percentof the composition as metallic iron. The solid had an initial BETsurface area of about 41 m² /g. The solid was impregnated with thalliumnitrate by the technique of incipient wetness using an aqueous solutionof thallium nitrate. After drying overnight in a vacuum oven at 110° C.,the solid had an Fe/Tl weight ratio of 100:10, taken as the free metals.

Catalyst Four (100 Fe:10 Tl, supported on Cs-doped alumina)

Beta aluminum trihydrate was impregnated with the required amount ofcesium nitrate using the wellknown technique of incipient wetness toyield a solid containing 10 mole percent cesium, taken as the metal. Theresultant solid was heated in an air oven at 870° C. for 8 hours andthen mixed with ferric nitrate crystals, which had been heated untilthey melted and dissolved in their own water of crystallization(approximately 80°-85° C.). The resulting impregnated solid was thenplaced in an air oven at 110° C. for 12 hours, and under theseconditions, decomposition of the nitrate to the oxide occurred yieldinga solid containing 10 weight percent each of Fe and Cs, taken as thefree metals. Then, by the incipient wetness technique, the solid wasimpregnated with thallium nitrate to yield a solid having a Fe/Tl weightratio of 100:10.

Catalyst Five (100 Fe:10 Tl, unsupported)

This catalyst was prepared as described above for Catalyst Two, exceptthat commercially available iron oxide, as opposed to precipitated ironoxide, as used for Catalyst Two, was impregnated with thallium nitratesolution by the technique of incipient wetness, wherein the weight ratioof Fe/Tl, taken as the free metals, was 100:10.

Catalyst Six (100 Fe:10 Tl:2F, unsupported)

This catalyst was prepared by adding an aqueous solution of ammoniumfluoride, by the technique of incipient wetness, to Catalyst Five,described above. The resulting catalyst contained Fe/Tl/F, in a weightratio, as the free elements, of 100:10:2.

Catalyst Seven (100 Fe:20 Tl, supported on Al₂ O₃)

This catalyst was prepared by the procedure described above for CatalystTwo, except that the incipient wetness impregnation step was performedtwice with aqueous thallium nitrate yielding a resulting solid having anFe/Tl weight ratio of 100:20 taken as the free metals.

Catalyst Eight (100 Fe:20 Tl:2F, supported on Al₂ O₃)

This catalyst was prepared by adding ammonium fluoride to the CatalystSeven, described above, by the technique of incipient wetness resultingin a catalyst having the composition of 100 Fe:20 Tl:2F, by weight,taken as the free elements, on Al₂ O₃.

Catalyst Nine (100 Fe:10 Tl, as the chloride)

This catalyst was prepared by impregnating iron oxide with aqueousthallium chloride by the technique of incipient wetness, as describedabove for Catalyst Five, except that thallium chloride was used insteadof thallium nitrate, yielding a solid having an Fe/Tl weight ratio of100:10, as the free metals.

Catalyst Ten (100 Fe:52.3 Zn:10 Tl)

An iron-zinc catalyst, 100 Fe:52.3 Zn:10 Tl, was prepared according tothe general procedure of Example 1 except that zinc nitrate was used inplace of cobalt nitrate.

Catalyst Eleven (2.5 Fe:1Tl, unsupported)

A catalyst was prepared according to the general procedure for CatalystTwo, except that the thallium nitrate loading was adjusted so that thefinal composition had an atomic ratio of Fe/Tl of 2.5/1, (correspondingto an Fe/Tl weight ratio of 100:150).

Catalyst Twelve (4Fe:1Tl, supported on MgO--Al₂ O₃

A catalyst prepared consisted of iron promoted with thallium (Fe/Tlweight ratio 4:1) supported on a magnesium-alumina spinel. Thissupported catalyst contained 5 weight percent of iron. The catalyst wasprepared by melting 90 g. of ferric nitrate at 80° C. in a largeevaporating dish. To this liquid was added 4.0 g. of thallium nitrateand 250 g. of spinel support with constant stirring in order to insureuniform and total impregnation. The solid was placed in a vented ovenmaintained overnight at 200° C. at which temperature the nitrates wassubstantially decomposed to the respective oxides.

EXAMPLE 4

The catalysts prepared and described in Examples 1-3 were run underFischer-Tropsch conditions at elevated temperatures and the runs allproduced liquid hydrocarbons in the C₆ -C₁₁ range, containing C₆ -C₁₁aromatics, C₂ -C₁₅ alpha olefins and low amounts of C₂₃₊ wax.

EXAMPLE 5

A 10:1 Fe/Tl catalyst was prepared by the incipient wetness technique,as described above in Example 2 and tested by the following procedurefor Fischer-Tropsch synthesis.

The catalyst was tested in a fixed bed tubular reactor fitted with ahighly conductive brass sleeve. Catalyst pretreatment consisted offlowing a mixture of H₂ /CO/N₂ (49:50:1, by volume, approx.) over thecatalyst at 270° C., 1 atm. pressure, and a space velocity of 500v/v/hr. for 18 hours. The pressure was then raised to 120 psia. Thepretreatment was continued for two more hours at which time thetemperature was maintained at 270° C. or increased in the range of 270°to 375° C. The space velocity was adjusted in the range of 150 to 1200v/v/hr. Liquid samples were collected at 4° C. and gas analyses wereperformed by in-line gas chromatography. A highly conductive brasssleeve was placed in the 3/4 inch space between the surrounding furnaceand the 1/2 inch O.D. stainless steel 5" long reactor tube. Thispresumably has two favorable effects: (1) it prevents natural convectionof air which tends to lead to axial temperature gradients; and (2) itnormalizes and dissipates temperature gradients created by heats ofreaction. A traveling 1/16 inch thermocouple positioned in a 1/8 inchO.D. stainless steel tube at the reactor center indicated that the axialtemperature gradients in the reactor were reduced to ˜1° C./cm up to300° C. and to ˜2°-5° C./cm up to 350° C.

The performance of thallium-promoted iron under these conditions isshown in the following tables:

                  TABLE I                                                         ______________________________________                                        CO Conversion:                                                                Temp.      Space Velocity                                                                            CO Conversion                                          ______________________________________                                        270°                                                                              150-1200    90-20%                                                 300°                                                                              150-1200    65-40%                                                 325°                                                                              150-1200    96-80%                                                 350°                                                                              150-1200    97-90%                                                 ______________________________________                                    

                  TABLE II                                                        ______________________________________                                        Methane Selectivity:                                                                                 CH.sub.4 (% of Total                                   Temp.      Space Velocity                                                                            Hydrocarbon)                                           ______________________________________                                        270°                                                                              150-1200    6-4%                                                   300°                                                                              150-1200    6-3%                                                   325°                                                                              150-1200     6-10%                                                 350°                                                                              150-1200     9-15%                                                 ______________________________________                                    

                  TABLE III                                                       ______________________________________                                        Liquid (C.sub.5 -C.sub.11) Selectivity:                                                              C.sub.5 -C.sub.11                                      Temp.      Space Velocity                                                                            (% of Total HC)                                        ______________________________________                                        270°                                                                              150-1200    50-54%                                                 300°                                                                              150-1200    51-57%                                                 325°                                                                              150-1200    50-51%                                                 350°                                                                              150-1200    42-51%                                                 ______________________________________                                    

                  TABLE IV                                                        ______________________________________                                        Gas (C.sub.4.sup.-)Selectivity                                                Temp.     Space Velocity                                                                            C.sub.4.sup.- (% of Total HC)                           ______________________________________                                        270°                                                                             150-1200    35-30%                                                  300°                                                                             150-1200    34-26%                                                  325°                                                                             150-1200    35-39%                                                  350°                                                                             150-1200    39-50%                                                  ______________________________________                                    

                  TABLE V                                                         ______________________________________                                        α-Olefin Selectivity in C.sub.6.sup.+ Fraction:                         Olefin                 C.sub.6.sup.+ α                                  Temp.      Space Velocity                                                                            (% of Total HC)                                        ______________________________________                                        270°                                                                              150-1200    21-26%                                                 300°                                                                              150-1200    23-26%                                                 325°                                                                              150-1200    21-16%                                                 350°                                                                              150-1200    14-8%                                                  ______________________________________                                    

                  TABLE VI                                                        ______________________________________                                        Aromatics Selectivity:                                                                               Aromatics                                              Temp.      Space Velocity                                                                            (% of Total HC)                                        ______________________________________                                        270°                                                                              150-1200    2-3%                                                   300°                                                                              150-1200    2-3%                                                   325°                                                                              150-1200    4-8%                                                   350°                                                                              150-1200     7-14%                                                 ______________________________________                                    

As is initially seen in the above data, Fe/Tl catalyst is an activeFischer-Tropsch catalyst for producing hydrocarbons.

Further, it was observed that under the process conditions used, therewas a relatively weak dependence on the space velocity in the processwith respect to methane selectivity, liquid C₅ -C₁₁ selectivity, gaseousC₁ -C₄ hydrocarbons, alpha-olefin and aromatic selectivity. However, asignificant dependence of percent CO conversion on space velocity wasobserved particularly at lower temperatures.

EXAMPLE 6

Utilizing the general procedure described in Example 5, the followingruns were made with a catalyst of the composition: 100 Fe:20 Tl;prepared as described in Example 2. Portions of the same catalyst batchwere run under substantially the same conditions in three differentreactors to determine possible apparatus effects in the data. Run No. 3was conducted in the apparatus described in Example 5, and runs 1 and 2were conducted in other fixed bed tubular reactors. The reactors used inRuns 1 and 2 were similar to the apparatus described in Example 5,except that the bed length used in Run 1 was about 36" long, and the bedlength used in Run 2 was about 3" long. The three runs were conducted at270° C., at a pressure of 0.9 MPa and a feedstream containing a CO/H₂molar ratio of 1.0. Results are given below.

                  TABLE VII                                                       ______________________________________                                        Comparison of 100 Fe:20 Tl Catalyst at 270° C. in Three                Different Reactors; P = 0.9 MPa, Feed = 1.0 CO/1.0 H.sub.2                    Run           1          2       3                                            ______________________________________                                        GHSV          300        300     375                                          Run Time (min.)                                                                             1380       1311    1080                                         % CO Conversion                                                                             76         53      51                                           Selectivity, wt. %                                                            of Hydrocarbons                                                               CH.sub.4      5.2        7.4     6.7                                          C.sub.2 H.sub.4                                                                             4.8        6.4     3.2                                          C.sub.2 H.sub.6                                                                             1.4        2.0     3.3                                          C.sub.3       12.8       21.3    10.8                                         C.sub.4       16.8       17.4    10.4                                         C.sub.5 +     59         43      65                                           % Aromatics in                                                                C.sub.6       1.1        N.M.sup.(a)                                                                            1                                           C.sub.7       2.5         9      3.3                                          C.sub.8       6.5         6      9.1                                          C.sub.9       6.7                12.9                                         C.sub.10                         11.1                                         C.sub.11                         2.7                                          ______________________________________                                         .sup.(a) N.M. = Not Measured.                                            

As is seen from the data there is general agreement in hydrocarbonselectivities. The small differences among the runs can be attributed tothe slight variations in the reactor configurations and run conditions.

EXAMPLE 7

Utilizing the procedure and different sets of apparatus described inExample 6, the same catalyst was tested under the same conditions, butat 325° C. Results are given in the following table.

                  TABLE VIII                                                      ______________________________________                                        Comparison of 100 Fe:20 Tl Catalyst at 325° C. in Three                Different Reactors; P = 0.9 MPa, Feed = 1.0 CO/1.0 H.sub.2                    Run           1          2       3                                            ______________________________________                                        GHSV          300        300     200                                          Run Time (min.)                                                                             1320       1387    1080                                         % CO Conversion                                                                             97         95      97                                           Selectivity, wt. %                                                            of Hydrocarbons                                                               CH.sub.4      5.8        8.1     14.2                                         C.sub.2 H.sub.4                                                                             4.1        3.5      2.4                                         C.sub.2 H.sub.6                                                                             2.4        4.3      3.8                                         C.sub.3       12.5       18.9    11.0                                         C.sub.4       14.7       13.0    10.0                                         C.sub.5 +     60         52      61                                           % Aromatics in                                                                C.sub.6       2.8         4       4.7                                         C.sub.7       8.2        17      11.2                                         C.sub.8       12.0       13      15.6                                         C.sub.9       13.0               15.7                                         C.sub.10                         13.6                                         C.sub.11                          5.8                                         ______________________________________                                    

As is seen from the data, there is good general agreement in thehydrocarbon selectivities.

EXAMPLE 8

Example 6 was repeated utilizing the same catalyst, the same apparatus,and the same process variables, except that the temperature was raisedto 350° C. Results are given below in the Table IX.

                  TABLE IX                                                        ______________________________________                                        Comparison of 100 Fe:20 Tl Catalyst at 350° C. in Three                Different Reactors; P = 0.9 MPa, Feed = 1.0 CO/1.0 H.sub.2                    Run           1          2       3                                            ______________________________________                                        GHSV          377        386     300                                          Run Time (min.)                                                                             1300       1170    1440                                         % CO Conversion                                                                             96         95      45                                           Selectivity, wt. %                                                            of Hydrocarbons                                                               CH.sub.4       7.2       9.6     16.6                                         C.sub.2 H.sub.4                                                                              4.7       4.4      1.3                                         C.sub.2 H.sub.6                                                                              2.4       3.3      4.2                                         C.sub.3       12.6       17.0    10.2                                         C.sub.4       14.6       13.2     7.4                                         C.sub.5 +     58         54      60                                           % Aromatics in                                                                C.sub.6       12.3       19      16.7                                         C.sub.7       25.4       36      33.3                                         C.sub.8       28.2       34      31.9                                         C.sub.9       28.8               29.3                                         C.sub.10                         22.0                                         C.sub.11                         11.2                                         ______________________________________                                    

As is seen from the data, the hydrocarbon selectivities again show goodagreement.

EXAMPLE 9

The following runs were made in the apparatus described in Example 5using the same 10:1 Fe/Tl described in Example 5, the 20:1 Fe/Tlcatalyst described in Example 6, and a 100 Fe:4K catalyst, prepared bythe technique described in Example 2, except that sufficient K₂ CO₃ wasused to achieve a 4 weight percent potassium loading. (Note: thepretreatment procedure given to Catalyst C was the same as for the othercatalysts, for comparative purposes, and did not include the morevigorous high temperature sintering step which would normally beadministered). Also tested was a commercial ammonia synthesis catalyst,Catalyst D. The runs were made at 0.9 MPa, with a 1:1 by volume CO/H₂feed. The particular temperatures and space velocities (GHSV) used aregiven in the following Tables. Table X lists the percent CO conversion,percent selectivity to hydrocarbons, percent methane produced, percentC₁ -C₅ hydrocarbons produced and percent C₆ -C₁₁ liquid hydrocarbonsproduced. Table XI lists percent of CO which is converted to: C₁₂ -C₂₃hydrocarbons, wax (C₂₃₊), aromatics, and alpha-olefins.

Catalyst A is 100 Fe:10 Tl;

Catalyst B is 100 Fe:20 Tl;

Catalyst C is 100 Fe:4K; and

Catalyst D is a commercial NH₃ synthesis catalyst.

                                      TABLE X                                     __________________________________________________________________________    Results of Integral Reactor Studies of CO Hydrogenation                       over Iron Catalysts: Conversion of Selectivity to Lighter                     Products: P = 0.9 MPa, Feed = 1.0 CO/1.0 H.sub.2                                                 % CO                                                                              %   %  %   %                                           Run Catalyst                                                                           Temp., °C.                                                                   GHSV                                                                              Conv                                                                              Selec                                                                             CH.sub.4                                                                         C.sub.1 -C.sub.5                                                                  C.sub.6 -C.sub.11                           __________________________________________________________________________    1   A    270   300 78.6                                                                              64.6                                                                               4.5                                                                             35.0                                                                              46.2                                        2   A    270   300 46.8                                                                              69.9                                                                               3.4                                                                             30.4                                                                              44.8                                        3   A    300   300 62.5                                                                              61.9                                                                               3.5                                                                             39.0                                                                              44.6                                        4   A    300   300 78.1                                                                              60.4                                                                               4.5                                                                             37.3                                                                              46.4                                        5   A    325   300 95.5                                                                              58.8                                                                               7.8                                                                             42.0                                                                              45.0                                        6   A    350   300 96.7                                                                              60.9                                                                              10.1                                                                             38.4                                                                              45.3                                        7   A    350   300 63.6                                                                              62.5                                                                              13.0                                                                             44.7                                                                              45.4                                        8   A    375   300 55.4                                                                              56.2                                                                              21.9                                                                             52.8                                                                              38.4                                        9   A    400   300 81.6                                                                              54.9                                                                              21.0                                                                             48.4                                                                              39.1                                        1   B    270   150 81.9                                                                              63.4                                                                               5.2                                                                             43.3                                                                              47.8                                        2   B    270   150 88.1                                                                              65.4                                                                               5.8                                                                             38.8                                                                              45.5                                        3   B    270   375 50.6                                                                              66.7                                                                               6.7                                                                             45.2                                                                              42.2                                        4   B    300   150 97.7                                                                              65.6                                                                               5.7                                                                             44.5                                                                              45.6                                        5   B    325   200 97.2                                                                              64.7                                                                              14.2                                                                             62.5                                                                              31.6                                        6   B    350   300 45.0                                                                              59.6                                                                              16.6                                                                             46.6                                                                              39.0                                        7   B    375   300 33.6                                                                              62.6                                                                              23.6                                                                             55.2                                                                              35.0                                        1   C    270   300 68.9     3.0                                               2   C    300   300 51.1                                                                              60.5                                                                               6.8                                                                             21.2                                                                              27.5                                        3   C    325   300 89.5                                                                              54.8                                                                              11.6                                                                             29.2                                                                              30.0                                        4   C    350   300 55.5                                                                              66.0                                                                              11.1                                                                             31.8                                                                              32.5                                        5   C    375   300 33.6                                                                              64.1                                                                              10.6                                                                             38.2                                                                              47.2                                        1   D    350   300 97.1                                                                              69.5                                                                               3.3                                                                             42.2                                                                              42.3                                        __________________________________________________________________________

                  TABLE XI                                                        ______________________________________                                        Results of Integral Reactor Studies of CO Hydrogenation                       over Iron Catalysts: Selectivity to Heavier                                   Products, Aromatics and α-Olefins                                                      % CO Converted to                                                              Listed Products                                                     Cat-   Temp.,        C.sub.12 - Aro-                                    Run   alyst  °C.                                                                            GHSV  C.sub.23                                                                           C.sub.23.sup.+                                                                      matics                                                                              α-Olefins                   ______________________________________                                        1     A      270     300   18.1 0.7    3.32 22.52                             2     A      270     300   23.8 1.0    2.92 22.31                             3     A      300     300   15.5 0.9    3.87 21.31                             4     A      300     300   15.2 1.1    3.36 23.46                             5     A      325     300   12.8 0.2    6.83 18.38                             6     A      350     300   16.0 0.3   12.70 14.93                             7     A      350     300    9.7 0.2   14.02  9.66                             8     A      375     300    7.5 1.3   14.21  4.16                             9     A      400     300   12.4 0.1   20.44  4.44                             1     B      270     150    8.8 0.1    2.65 23.88                             2     B      270     150   14.1 1.6    4.01 16.39                             3     B      270     300    9.8 2.8    2.73 15.17                             4     B      300     150    9.8 0.1    2.17 22.53                             5     B      325     150    5.8 0.1   3.2   14.61                             6     B      350     300   13.6 0.8   10.3  10.0                              7     B      375     300   10.0 -0.2  11.2  10.7                              **1   C      270     300                                                      2     C      300     300   37.5 13.8   3.36 23.46                             3     C      325     300   31.2 9.6   4.6   13.6                              4     C      350     300   24.9 10.8   6.57 16.69                             5     C      375     300   13.5 1.1   13.26  6.14                             1     D      350     300   14.8 0.7    8.65 11.43                             ______________________________________                                         **Wax buildup                                                            

Key results are given in Tables X and XI. Percentage conversion of COand the percentage selectivity of this conversion to hydrocarbons aregiven in the 5th and 6th columns of Table X, respectively. In general,it has been found that a potassium-promoted iron catalyst losessubstantial hydrocarbon synthesis activity within relatively shortperiods of time as contrasted to thallium-promoted iron catalyst, whichmaintains a higher hydrocarbon synthesis activity for longer periods oftime. selectivities of CO conversion to hydrocarbons ranged consistentlybetween 54 to 70 percent for all catalysts. Methane selectivity (weightpercentage of CH₄ in hydrocarbon products) appears to correlate withtemperature, ranging from 4 percent at 270° C. to 22 percent at 375° C.This correlation was statistically significant for all three catalysts(p<0.05).

Differences between Fe/Tl and Fe/K catalyst in C₁ -C₅, C₆ -C₁₁, C₁₁ -C₂₃and C₂₃₊ selectivities clearly exist. The Fe/Tl catalyst tends to makeligher products than Fe/K (columns 8 and 9 in Table X and columns 5 and6 in Table XI). Virtually no wax is made by Fe/Tl, whereas 10 percent ofthe hydrocarbons (by weight) made by Fe/K are in the C₂₃₊ range.

The aromatics yield, as a percentage of total hydrocarbons produced, isseen to increase with temperature for all three catalysts. For 100 Fe:10Tl, this correlation is significant (p<0.01), but is not quitesignificant for 100 Fe:20 Tl or 100 Fe:4K. At 300° to 325° C., thelatter two catalysts appear similar in this respect, but at 350° C., 100Fe:10 Tl produces about twice as much aromatics as does 100 Fe:4K. Above350° C., the Fe/K catalyst plugged and lost activity, probably due tocoke formation. On the other hand, wax accumulated on this particularcatalyst at temperatures below 325° K., greatly complicating the productassay. Thus, comparative experiments outside the temperature range of325° to 350° C. are difficult to perform with Fe/K.

There is a rather striking statistical negative correlation between thepercentages of aromatics and α-olefins in the C₆ -C₁₁ cut indicating aninverse relationship. Because α-olefins are thought to be primaryproducts of Fischer-Tropsch synthesis, this suggests that olefins areconverted to aromatics and that the rate of this conversion increaseswith temperature.

From the data, Fe/Tl catalyst appears to make a lighter and narrowerproduct distribution than Fe/K where the two catalysts are pretreatedunder substantially the same conditions not involving sintering. Inaddition, Fe/Tl has good total selectivity (percentage of converted COthat goes to hydrocarbons) and low selectivity to methane production.The aromatics yield of Fe/Tl is comparable to that obtained from Fe/Kexcept at >350° C., where it is difficult to obtain data on Fe/K due tocoking and deactivation, as described above. About 10 percent of thehydrocarbons (by weight) produced by Fe/Tl at 350° C. are aromatics. Inthe C₆ -C₁₁ cut range, this corresponds to 25 percent of the cut. Thus,the C₆ -C₁₁ cut represents an attractive feedstock for an aromaticsseparations process.

EXAMPLE 10

To show that the catalyst must be pretreated to yield metallic thalliumand reduced and carbided iron, the pretreatment was only partiallycompleted, yielding metallic thallium and a mixture of oxidized, reducedand carbided iron. It is necessary to operate the process at reducedtemperatures, below about 230° C., to ensure that iron in the catalystremains in this state of multiple valencies. Under these conditions,200° C., 8.2 atm to 16.3 atm, and 300 v/v/hr, essentially no aromatichydrocarbons were produced and a large fraction of the products were inthe form of oxygenated hydrocarbons and, especially, as alcohols. Thisform of the catalyst is the subject of a copending patent application.Following operation of the process at these lower temperatures, theprocess conditions were changed to complete the reduction and carbideformation, namely the temperature was increased to 270° C., the pressurewas maintained at 8.2 atm and the space velocity was maintained at 300v/v/hr. At these conditions, the alcohol yield decreased, as shown inTable XII. A corresponding increase in the yield of non-oxygenatedhydrocarbons, especially alpha olefins and paraffins, was observed asthe alcohol yield decreased. Concurrently, the catalyst became totallyreduced and carbided. The temperature was then again reduced to 175° to200° C., with the other conditions remaining constant, that is, thepressure was 8.2 atm and the space velocity was 300 v/v/hr. At theseconditions, the catalyst was not very active, as indicated by COconversions in the range of 10 to 15 percent. This shows that theprocess for producing liquid hydrocarbons and aromatic hydrocarbons inthe C₆ -C₁₁ range is preferably carried out at higher temperatures inthe range of 250° to 550° C., preferably 270° to 400° C., and that thecatalyst should be fully pretreated to yield a working catalystconsisting substantially of metallic thallium and reduced and carbidediron.

                  TABLE XII                                                       ______________________________________                                                        Time (hours)                                                               23   71        95    167                                         ______________________________________                                        % CO Conv.     65     64        65  68                                        CO.sub.2 Sel..sup.(a)                                                                        31     32        30  32                                        HC Sel..sup.(b)                                                                              69     68        70  68                                        C.sub.1 -C.sub.19 ROH.sup.(c)                                                                17.9   8.4       8.1 7.0                                       C.sub.6 -C.sub.12 ROH.sup.(d)                                                                 3.8   2.0       2.2 1.9                                       % C.sub.6 -C.sub.12 ROH.sup.(e)                                                              12.6   5.4       5.3 5.0                                       % Methane.sup.(f)                                                                             4.3   4.7       4.5 4.8                                       ______________________________________                                         .sup.(a) Percent CO converted to CO.sub.2.                                    .sup.(b) Percent CO converted to total hydrocarbons including alcohols.       .sup.(c) C.sub.1 -C.sub.19 alcohols produced as weight percent of total       produced hydrocarbons.                                                        .sup.(d) C.sub.6 -C.sub.12 alcohols as weight percent of total produced       hydrocarbons.                                                                 .sup.(e) Weight percent C.sub.6 -C.sub.12 alcohols of C.sub.6 -C.sub.12       produced hydrocarbons.                                                        .sup.(f) Percent methane produced as weight percent of total produced         hydrocarbons.                                                            

What is claimed is:
 1. A process for producing liquid hydrocarbons,including those in the C₆ -C₁₁ hydrocarbon range, comprising the stepsof:(a) first depositing thallium on the surface of a supported orunsupported iron catalyst wherein the weight ratio of iron-thallium,taken as the free metals, is from about 100:1 to 1:100, and wherein saidiron compounds contain iron value substantially in the trivalent state;(b) contacting said iron-thallium catalyst with a mixture of CO and H₂in a volume ratio of about 1:4 to 4:1, respectively, at a temperatureranging from 270° to 550° C., a pressure ranging from 0.1, to 10 MPa anda space velocity ranging from 10 to 10,000 v/v/hr., or equivalentconditions, for a sufficient time to substantially convert said thalliumcompounds to metallic thallium and said iron compounds to reduced andcarbided iron; and (c) continuing said contacting as described in step(b) at a pressure above 0.1 MPa, a temperature ranging from 230° to 550°C., to produce liquid hydrocarbons comprising about 40 weight percentand greater C₆ -C₁₁ liquid hydrocarbons and below about 5 weight percentC₂₃₊ hydrocarbons.
 2. The process of claim 1 wherein said product C₆-C₁₁ hydrocarbons comprise at least about 5 weight percent of C₆ -C₁₁aromatic hydrocarbons.
 3. The process of claim 2 wherein saidtemperature is 350° C. and above in step (b) and said C₆ -C₁₁ producthydrocarbons comprise about 10 weight percent C₆ -C₁₁ aromatichydrocarbons.
 4. The process of claim 1 wherein said temperature is 270°to 350° C. in step (b) and said liquid product hydrocarbons compriseabout 20 weight percent and greater C₆ -C₁₁ alpha olefins.
 5. Theprocess of claim 1 wherein said C₂₃₊ hydrocarbons are present in lessthan three weight percent.
 6. The process of claim 1 wherein the weightratio of iron-thallium, taken as the free metals, is from about 100:1 toabout 35:65.
 7. The process of claim 6 wherein said weight ratio ofiron-thallium, taken as the free metals is from about 100:10 to 80:20.8. The process of claim 1 wherein said catalyst is supported on Al₂ O₃,alkali-doped Al₂ O₃, SiO₂, TiO₂, MgO, MgCO₃, silicon carbide, zirconia,or mixtures thereof.
 9. The process of claim 1 wherein said compounds ofiron and thallium are selected from their oxides, hydroxides,carbonates, sulfates, carbides, halides, nitrates, or mixtures thereof.10. The process of claim 9 wherein said iron compound is iron oxide. 11.The process of claim 9 wherein said thallium compound is thallium oxide,thallium chloride, thallium fluoride, thallium nitrate, or mixturesthereof.
 12. The process of claim 1 wherein said catalyst compositionfurther contains a promoter agent.
 13. The process of claim 12 whereinsaid promoter agent is selected from cobalt, zinc, chromium, manganese,barium, as their salts or oxides, ammonium fluoride, potassiumcarbonate, or mixtures thereof.
 14. The process of claim 1 wherein themixture of CO and H₂ in step (b) is in a volume ratio of about 2:1 to1:2, respectively.
 15. The process of claim 1 wherein said temperaturein step (b) is about 270° to 400° C.
 16. The process of claim 1 whereinsaid pressure in step (b) is about 0.5 to 1.5 MPa.
 17. The process ofclaim 1 wherein said catalyst is in the form of a fixed bed.
 18. Theprocess of claim 1 wherein said catalyst is in the form of a fluid bed.19. The process of claim 1 wherein said first contacting in step (a) iscarried out at 270° C., 0.1 MPa pressure, a space velocity of 300 to 500v/v/hr. using a mixture of CO and H₂ at a volume ratio of 1:1,respectively.
 20. The process of claim 1 wherein said velocity in step(b) is in the range of 100 to 2500 v/v/hr.
 21. A process for producingliquid hydrocarbons, including those in the C₆ -C₁₁ hydrocarbon range,comprising the steps of:(a) first depositing thallium nitrate or oxideon the surface of a supported iron catalyst to form an iron-thalliumcatalyst the weight ratio or iron:thallium, taken as the free metals inthe composition, being from about 100:1 to 65:35, said support beingaluminum oxide, magnesium oxide or mixtures thereof; (b) contacting saidiron thallium catalyst with a mixture of CO and H₂ at a volume ratio of1:1 at about 270° C., at 0.1 MPa pressure, a space velocity of 300 to500 v/v/hr, for a sufficient time to substantially convert said thalliumcompound to metallic thallium and said iron oxide to reduced andcarbided iron; and (c) continuing said contacting as described in step(b) at a temperature ranging from 270° to 350° C. a pressure rangingfrom 0.5 to 1.5 MPa, and a space velocity ranging from 150 to 1500v/v/hr, to produce hydrocarbons comprising C₆ -C₁₁ liquid hydrocarbonscomprised of about 20 weight percent alpha olefin hydrocarbons and lessthan about one weight percent C₂₃₊ hydrocarbon waxes.
 22. A process forproducing liquid hydrocarbons, including those in the C₆ -C₁₁hydrocarbon range, comprising the steps of:(a) first depositing thalliumnitrate or oxide on the surface of a supported iron oxide catalyst toform an iron thallium catalyst, the weight ratio of iron:thallium, takenas the free metals in the composition, being from about 100:1 to 65:35,said support being aluminum oxide, magnesium oxide, or mixtures thereof;(b) contacting said iron thallium catalyst with a mixture of CO and H₂at a volume ratio of about 1:1 at about 270° C., at 0.1 MPa pressure, aspace velocity of 300 to 500 v/v/hr, for a sufficient time tosubstantially convert said thallium compounds to metallic thallium andsaid iron oxide to reduced and carbided iron; and (c) continuing saidcontacting described in step (b) at a temperature ranging from 350° to550° C., a pressure ranging from 0.5 to 1.5 MPa, and a space velocityranging from 150 to 1500 v/v/hr, to produce hydrocarbons comprising C₆-C₁₁ liquid hydrocarbons comprised of at least about 25 weight percentC₆ -C₁₁ aromatic hydrocarbons and less than about one weight percentC₂₃₊ hydrocarbon waxes.